RESUMEN
The study included 40 diarrheic children under 3 years of age [20 acute and 20 chronic cases] and 20 age matched controls. Fecal specimens were collected from each. Isolation and characterization of non spore forming Gram-negative anaerobic rods was carried out by using non selective media [CDC and blood agar] and selective media [KVA and PVA] media, Gram stain, relationship to oxygen, fluorescence and spot tests. Presumptive identification was done by using several biochemical identification systems [presumpto plates, rapid enzyme systems and API 20 A]. Definitive identification was carried out by using gas liquid chromatography and toxin assays on B. fragilis isolates by using tissue culture cell lines [HELF and VERO] and by inoculation [intraperitoneal and intravenous] in 3-week old mice